Safety is a critical objective for systems that may cause harm if component or system failure is unmitigated, such as in automotive systems. Functional Safety of automotive analog and mixed-signal circuits face several challenges. With more evolving safety-critical applications in automotive domain, e.g. ADAS (Advanced Driver Assistance Systems) and Autonomous Driving, it becomes key to assure functional safety of electrical and/or electronic (E/E) systems within road vehicles. Functional Safety (FuSa) is defined in International Organization for Standardization (ISO) 26262, as the absence of unreasonable risk due to hazards caused by malfunctioning behaviors of E/E systems. ISO 26262, with the first version released in 2011 and the second version due in 2018, is an international standard to regulate the safety life cycle, risk analysis, safety management, safety concept development and validation activities of automotive E/E systems. The Automotive Safety Integrity Level (ASIL: A-D) defines the safety requirements associated with a function of the system and its criticality. An ASIL target needs to be achieved by a synergic system design such that, even in conditions of failure, there is a sufficient margin of safety for the human user, e.g. driver or passenger. However, the increasing complexity of automotive E/E systems makes it challenging to reach a high ASIL level target (e.g. ASIL-D) in vehicles.
According to ISO 26262, Fault Tolerance Time Interval (FTTI) is defined as a minimum time span from occurrence of a fault in an item (i.e. vehicle) to occurrence of a hazardous event, if a safety mechanism is not activated. A safety mechanism consists of fault detection and fault reaction, thus the Fault Handing Time Interval (FHTI), i.e. a sum of the fault detection time interval and the fault reaction time interval, should be less than FTTI, in order to achieve the expected safety goal. Consequently any early detection that helps reduce the total fault handling time is much desirable from functional safety perspective. However, existing standards and systems focus on corrective action when a failure occurs.